It is thought that cancer stem cells are the main cause of recurrence or metastasis of cancer, and the importance of targeting cancer stem cells in cancer therapy has been pointed out. However, the proportion of cancer stem cells in tumor tissue is very low (Non-Patent Document 4), and it is very difficult to specifically recognize and treat cancer stem cells. The development of techniques for detecting cancer stem cells and new therapies targeting cancer stem cells are important issues in cancer care.
Currently, molecular markers such as CD133, CD24, and CD44 are known as a cancer stem cell marker (Non-Patent Documents 1 to 7), but it is said that they are effective only in a few sort of cancer cells, and it is necessary to identify new molecular markers in order to detect cancer stem cells in a greater variety of cancers.